I think its safe to say that everyone usually starts on a Bach 1 1/2 G. the Schilke equivalent to that is the 58. Then we go through a steroid period that says "uhhh, thats not big enough" and we jump up to the Schilke 60. After a few months/years of beating our faces up, some of us scale back a tad, realizing that a lead pipe is USEFULL and we are not Charlie Vernon.
Once the player figures out what works for them - sharp rim, round rim; extra mass, scaled down; custom, off the rack, some popular choices then become Bach 1 1/4, Schilke 59/60, Yamaha Doug Yeo, some Doug Elliot combo, or Greg Black (which is my choice.)
Bach 1 1/2 G, Schillke 58. That is usually where the journey begins.
Jay Heltzer
Tubenet lurker
bass trombone
USAF Ceremonial Brass (after BMT, staring next week - GULP!)