A few weeks ago I sold an MS290 to a guy who, at first, disputed that the saw was indeed an MS290 but was instead an 029. My first thought was, "Geeze, I'd RATHER have the older non-EPA stuff provided the saw is a good one" (which it was). Well, the saw was indeed an MS290 (thank you, Andy) but I was amazed that in the process of figuring things out the fellow said "I ONLY work with MS290s." Everything worked out just fine (he was a good guy, actually), but there are some folks out there who will always choose differently. The guy just LIKED them for some reason, probably because he had had a generally good experience with them.
Provided the 61 is in good nick, my vote is for the 61. Bulletproof, lots of used parts still out there, easy to work on, many upgrade possibilities, and lots of low-end grunt. You will find it a bit heavy and slow, but you can say that about the 029/MS290 also.
Just me talking, but I feel the need to remind you that you're not just limited to those two saws. I'm a 61 fan, but it IS old. You don't have to spend too much more money (if any more at all) to get a saw that is lighter and faster.