Philips? GE? Sylvania? I've been underwhelmed by how a batch of Sylvania F40 T12 Cool whites has been performing (lots of banding and flickering on magnetic ballasts until they get good and warm.) Do modern tubes perform worse than the vintage GE Mainlighters I've been using.

Everything has less mercury now, but of the big three GE seems to be the best in regard to producing decent output when cold, at least in most sizes.

Sylvania and GE would be best picks.  Phillips quality flat out sucks for the past 10 or so years.  My choice would be Sylvania.  The stuff released in the past 2-3 years has been great, bright output at start up.  I've installed several hundred 3500 tubes in the past several years. 

Do the Philips F40T12 lamps also suck? I plan to pull the T12s I have out of the American Fluorescent instant start fixtures I have now that I realize that they don't drive the T12s properly even though they're listed. So I'll have a few spare T12 bulbs but I'll eventually either need to buy some or convert the rest of my fixtures to T8. The two lamps I can easily get in case quanties in 3500K are the Philips T12 from Home Depot, and Sylvania T8- either 82 CRI from Menards or 90 CRI from Fleet Farm.

Not too sure.. Haven't run any new T12 Phillips lately. 

GE F32T8/SPX35

For F40T12, believe it or not the Philips Altos aren't bad at all, though they don't seem to be the longest lived.