I see this question all the time on several forums. The one thing that is seldom considered is the number of tubes each tester has testing data for. Some roll charts/data books have only a couple of hundred tubes listed. If you buy one of those, you will keep running into tubes you can't test. The tube tester I recommend is the military TV-7D because the complete tube data book is 100 pages.  The next best is the Hickok 539 B or C with 87 pages of testing data, but a nice one will cost around $1000.
The build quality of the TV-7 is also far better than any of the commercial Hickoks.

IMHO, the most important consideration in choosing a tube tester is the amount of testing data available. I think the military TV-7 is the winner, at least in the under $1000 class. The build quality is also a cut above the ones sold to TV repairmen. Those guys were expected to just buy a new tube tester every few years.

Thanks, AC5UP. I have the HP 410C manual, but although the two meters are functionally equivalent they are completely different inside. Sort of like the Hallicrafters and Hammarlund versions of the R274 receiver. The build quality of the Hickok is amazing. There are no carbon resistors or paper capacitors. The rotary switches are ceramic. I'm going to have to identify the adjusting pots on the top board in order to dial it in.
Roger  KF4ZQM

My Hickok 1605M  Multimeteris badly in need of calibration. There are six adjusting pots on the top circuit board but they are not marked. Does anyone have the instructions?