Who is your priority for walking?

Walk snorlax.i gave up on walking larvitar after getting to 35 candies because after evolving I would still need 92 candies to power it up. I switched back to zh/bs which I powered all the way up and now working on lick/bs lax. I'm at 30 candies so only 62 more :) snorlax has the huge advantage that there are no costs to evolve :)

I switch between Snorlax and Chansey. My 2 big bears are eating so much so I need to walk a lot (both are lvl 31.5). When they get full I switch to Chansey (still need 21 candies to evolve my 2nd Chansey).

My general policy is that I don't walk 5k pokemon outside of an event. After that I go by possible movesets. I walk pokemon that won't disappoint me. I was okay walking Charmander over 200km because I would have been happy with any moveset on Charizard. On the same note, I would have been upset to get steel wing/hyper beam on Dragonite AND he is a 5k buddy.

If your case, you are really far away on all of the stage 3 evolutions and both Larvitar and Dragonite can be disappointing. Ampharos could be just as disappointing, because Jolteon is simply a better option AND depending on you area, he might not even be gym viable...

That leaves Snorlax is you are set on one of those pokemon you listed.

Blissfulness.

I'm walking Chansey for quite some time now.
It's the most rare mon around here, and it's a top tier mon.

Got lucky with 5 good Chansey hatches.
Already evolved 3.
Two ZH/DG, one ZH/P.

Powered up one ZH/DG and now I need more candies to power up the other ZH/DG and evolve the remaining 2 Chanseys, in that order. Will not bother powering up the ZH/P, at least for now.

Walking Larvitar even though he's "uncommon" as a hatch since I haven't hatched any yet...that and he has the highest CP in gyms.

I still have over 150 Chancey candies (2 maxed) from pre-gen2 walking, earlier hatches and the event so I'm looking more to spread my powerups to different mons in case of gym meta changes.

Have enough Snorlax and Dragonite candies to max one if I ever get a good hatch so waiting on those for now. Sitting on 7 10km eggs (after hatching a poor IV Snorlax).

Hope to get 8 or 9 before Easter.

Switching between Snorlax and Chansey.

I've been walking several Chansey for the last 800 km. I already have 2 good Blissey (one level 33 and the other 31) but don't have anything better to walk. The day I hatch a decent Snorlax with good moves and IVs will change. But I may have maxed out 4 Blissey before I see that day...

I would walk the Snorlax; you are using him atm and he already has a good moveset. A new pokemon might end up with poor moves at which point it's just a pokedex entry. That said I wouldn't power your Snorlax past 30; after that powerups become less efficient and I would rather try and evolve a new 'mon.

Personally I just got done walking my Chansey so I could evolve her into a Blissey. She was already level 28 and I'm not in a hurry to power her to 30.

Right now I'm walking Mareep since he's a rare hatch. But I might switch to Porygon. Already have an Upgrade and a 82% Porygon, just need 15 more candies. Still debating because the Porygon is only level 7. So if I do want to get him to 30 that's a lot of candy...

1. Lapras 2. Larvitar (power up Tyrant) 3. Snorlax 4. Maybe Mapreep down the line

Depending on biome, Blissey and Snorlax are probably the best choices. Some people, desert biomes for example, see a good amount of Chansey so Snorlax would be the best choice -- but those in water biomes may prefer Blissey.

Beyond those two, I can see people walking with Dratini / Larvitar -- but those two are typically more common than the "elite" normal type defenders. I honestly wouldn't walk with anything else, because not much else is really too relevant in this meta, and you'll be able to complete oher stuff for the dex entries eventually.

I'd love to walk Mareep. I've hatched three and because of that I already have 67 candies. However, if Ampharos gets Focus Blast then it would've all been for nothing. That's why I'm walking Larvitar, and unfortunately it only hatched with 16 candies and it's the only one I hatched/caught, so it's going to be a very long walk but at the same time, I don't care about Tyranitar's moveset, I only want to stick it on top of gyms.

I walked chansey and got my first blissey.
Now im walking my second dragonite, he is missing 13 candys from being cp3000+.

Chansey/Blissey for me. Because she's the most rare among the ones you have mentioned. There are more Snorlax spawns then Chansey spawns.

Larvitar.
I have a hoard of Snorlax candy from some lucky hatches - I won't power up another Lax until PvP or a gym rework.
I am doing OK for Blissey, I have walked my only dnite to a point I am happy with it for now.
Once Larviatr is done, it will be Mareep, unless I get lucky on hatches between now and then.

At the moment I'm walking with a Larvitar because I naturally want Tyranitar. Need 28 more candies for that.

After that I'll probably pick Dratini because I hatched a couple today and only need 8 more candies to get my 2nd Dragonite.

Not sure which I'll pick as my Buddy after that. Will have to check what candies I need. If I can't decide, then I might go back to Chansey.

The only pokemons that i've buddied so far: Dratini, Snorlax, Lapras, Chansey, Larvitar. But right now i plan to buddy only Chansey and Larvitar.

I have buddied a dratini (until I caught a wild dragonite), snorlax, and aerodactyl; currently my buddy is my only chansey, hatched from an egg... just can't catch them here.

Would love to hatch a larvitar, which would be my next buddy after chansey.