This happened in a 2/5 game that's pretty normal. You got your bad players and your decent players. Nothing really noteworthy about it.

Hero: typical tag. I've shown some big hands down and I'm winning pretty good. I have $750.

V1: new to the table but has already doubled up by playing pretty aggressively. $400

V2: this player is probably the best at the table. He has made a few bad calls but has won most of his money off the 1 really bad fish at the table. He is still a good player and has $900

Hero limps under the gun with 55. Everybody but 1 player limps behind. So we are 7 handed going into the flop.

Flop ($35): 5 7 9 rainbow.

Hero leads out for $20
V1 in middle position raises to $60
V2 on the button flat calls

Hero?

From your description of the V's I find it hard to believe one of them has a set. If v1 is aggro he is raising pre with 77 or 99 and if v1 is the best player he is raising with those hands with 7 limpers OTB. I would put V1 on an OESD and V2 on Top pair most likely. I think you can flat here and continue betting for value on bricked turns and rivers.

I would agree that neither V has a bigger set given their styles. V1 could have an OESD but I think 2P and 68 are easily in his range as well. For V2, is he really gonna call a 3b after hero bets into 6 players with just TP? I doubt it if he's really the best player at the table. I think his range is 2pair/OESD/straight.

Call flop but I'm checking most turns IMO

Edit: I forgot raising was an option. What do you do if a scary card does come on the turn? Protect your hand now. If someone has 68 you still have outs to a FH

Yeah I can definitely see v2 on two pair or OESD as well but I don't think he has a straight here. Wouldn't you want to 4b a flopped straight on this board to protect from paired boards and higher straights getting there?

more than likely you could be up against straights here versus sets. ...combos of 6 8 have you crushed and theres also plenty of combo straight draws out their that they could have. As played I'd flat call the 40 and hope for the board to pair.....if the turn is a king and you fire 100 and the button raises you to 300 or so then I'd say its time to make a hero fold

Slow down a little bit.

Based upon your observation, what sort of hands does V1 play out of MP?

I was surprised to see a skilled player like V2 limp otb. How often have you seen him do this? What sort of hands might he do this with? Is he really that good? Is it possible he's been lucky tonight?

Now lets think about where V1 is at, on the flop. What part of his range does he raise with?

It depends in part on his image of you. If he thinks you're a fish, he will figure you could bet out 9x or even 7x, so he might not need much to raise. A draw would be plenty if he thinks you are weak/tight. Have you been?

And V2 calls? With what?? I certainly hope you've seen him make some loose calls here and there.

I'm kinda liking your relative position here; gives a man a chance to think, eh?

I think re raising folds out everything you beat, so I would flat the raise. Turn is tricky because leading out on safe turns looks so strong, I would c/c, and then c/decide rivers. If river pairs board I c/j, if not, depending on his sizing I would c/c or c/f

This is flat city .. and evaluate the Turn. I dont like V2 flatting and I dont like being OOP here. Please dont go nuts if the board pairs ...

c/c both safe Turns and Rivers so you can find out what V2 is doing on each street. GL