Re: Looking for the best Tube Screamer I can buy without spending too much!
Have you thought of getting an eq pedal and just boosting the freq you want for your leads. I've totally been backing away from OD'S and playing with less gain. Sounds so much bigger then before. If you have a modern hi gain amp chances are its got more then you need,you just need to take your time to dial it in.
Yes, I have a fully modded GE-7 EQ in the loop and works great but I use pedals for other things and I like variety! For example, sometimes I will run my J&J OD through my Bogner's clean channel just for a different low - medium gain flavor. For the same reason, I also love having the Xotic BB! Sometimes I also like the flavor it gives me goosing my gain channels with the pedal! Options baby, options...

I am also picking up a Mesa Electradyne and I thikn having a tube screamer type pedal would be a cool flavor to have for boosting solos or single notes lines.
Hard to say because I tend to favor the EQ in the loop like you or the built in Blow boost on my PWE or the built in boost on my Bogner Shiva.
Maybe I will just stick to two OD pedals, my lovely J&J OD and a little boost like the Xotic EP, Keeley Katana or Fulltone Fatboost. Options!
Plus with the Electradyne, some songs we do like Alice in Chains Them Bones, I want that tight high gain tone. The Xotic BB or J&J help it get there. Maybe I should skip the tube screamer or Xotic BB since the BB is a lot like a tube screamer.
Why do you think so many old school guys use tube screamers then? Maybe these are mostly guys using old non master Marshalls as a lead boost? I know the guys in Pearl Jam do this. Since my amps have channels and lots of gain on tap and an EQ in the loop...could be useless. Again options are still fun so I like having the J&J on the board and an Xotic Ep would be cool to grit up my clean and it is a pedal I could leave on! I hear people do the same with the Katana and Fatboost.