I too was a big fan of the sonic...straightest flying putter I have thrown. That being said, I found that it just got spit out of the chains much too often for my taste. I decided to give the gateway Magic a shot, and really love it. It feels good in the hands, flies straight, and stays in the basket. So right now it's my current putter.
Of the ones I've used:
Aviar - good all around disc, that I used for many years and enjoyed.
Coyote - Yeah, it's a midrange, but it was a sticky disc that flew well and grabbed the chains well, so I used it for a good while.
Sonic - See above...good disc though
Pig - liked it at first but I dunno...just didn't feel good in my hands and didn't like it from a distance.
Magic - Money...
I'll also add that I am pretty much a 100% lob putt....so that plays a big role in my choices. I like something that flies straight, lifts out of the hand easily and fast, yet will hold a line if I have to backhand it.
As for baskets: I picked up an In-Step basket for my practice and love it. It breaks down fast and easily, fits in my small trunk if I need to take it somewhere, and is solidly built. It goes for about 70-80 bucks, and you can find it on ebay or online somewhere. Just look up "In-Step disc golf" somewhere and you'll find it. Good bang for the buck. If you want more chains it's easy to do, although I haven't bothered.