The one phone I am doing most dev work on is the Evo V as that is the phone I use. Technically, I support the One V, but only loosely. Both of these are fantastic phones with good dev support and I would highly recommend them both. If you want a nice sleek phone, the One V is great, if you need the extra power, you would be best served by the Evo V. The Evo V has a minor radio issue expected to be fixed any day by an over the air upgrade. Rooted users already have the fix and have been enjoying their phones. I could live with either quite happily.
Most roms for the Venture and Optimus Elite are based on my work, however I mostly set them up so they had roms to work from. I only built the foundation roms for the Chaser, I have never even touched one. The Elite has some potential but also some issues, but has more development than the Chaser. It tends to stick in 1x, though it reads 3g and early models sometimes overheat.
I have no experience with the Samsung, but it, the Evo V and One V would be my main considerations. Word is we may also be getting the Galaxy S2, but it will be quite high priced.
Donate link is in my sig.