Questions to ask as I shop for a tonearm?

I’ll be upgrading in 6+ mos. I’m asking now because I’m still learning. I want to take plenty of time to understand the relevant technical aspects of something so complicated & what makes one person love brand X & another person dislike it.

I have a George Warren tt & a Sumiko Blackbird cart I’m waiting for to put on the stock Rega 250. I’m also waiting for Christmas to hookup a Jolida JD9 mkII.  My budget will be ~$1500. While brand & model suggestions are appreciated... I want to learn about tonearms. As always, I appreciate the knowledge you all pass on to me.
I've had a Grace 707 arm of 20 years and sold it; Maplenoll Ariadne air bearing arm/ turntable--the best I've had for sound up to now;  VPI Scout w/ arm; VPI Classic w/ arm; Avid Diva II w/ Origin Live Silver II arm; Super Lenco TT w/ OL Silver II arm; And then the same Lenco TT w/ Trans-Fi Terminator arm with all the upgrades.  The Lenco w/ Terminator was the overall second best set-up.  It did have the best dynamics and clarity of all of them.  I'll second the Trans-Fi Terminator for overall sound and use.  VERY TOUGH to find a TFT on the used market.  Mine was $1275 with everything including all parts of the air pump and delivery system.  I was hoping to at least equal the Maplenoll TT/ arm in sound and have it be less potentially dangerous to the cantilever in the air went out.  NEVER a problem with the TFT as it requires very little air to float the arm.

May have one for sale in the very near future.  I had to spend quite a bit more to beat the TFT.

@dorkwad TFT is back on sale apparently.  I think it may be too much for the OP to deal with.
@elizabeth The OP inherited the table and it's pretty decent except it comes with weak Rega 250 arm which s/he wants to change out. 
Check out the Jelco line of tonearms as they fall right in your budget and offer performance above your budget.
@tochsii - Some options...

If you are looking at  rega arm, then take a look at the Audiomods arms...

Jeff at Audiomods, will take note of your turntable/cartridge and make an arm that matches.

He uses a rega arm tube, but that is where all similarity to Rega arms ends. Everything else is built by him to a very high standard and level of performance. 

I would recommend the one piece silver litz tonearm wire and the VTA micrometer Adjustment options.

This is probably the last tonearm I will ever purchase

There are other Rega-like options available - like this one from Michell

If you decide on the Rega offering, then I would recommend the Cardas One piece harness. This was my first tonearm tweak and it performed really well compared to the stock Rega wire

Hope this helps in your quest - Steve

@williewonka Thanks for that post. I just bought an Audiomods V, which is at Sota to be mounted on the new Series Six Nova they are building for me now. My hunt (discussed in another thread) came down to the Audiomods or the new Jelco 850, 950s.  I am one who adjusts VTA for every LP played. An aftermarket VTA adjustment base made specifically for the Jelcos ~$200, kept it under consideration. The Audiomods has their own built-in micrometer as an option. A great deal on a pre-owned Audiomods w/micrometer from a fellow 'Goner made it an easy decision for me.

The Trans-Fi Terminator was something else I considered. Having spent plenty of time with a friends' TFT, I just couldn't get comfortable with its tweakiness and apparent fragility. The delicate exposed wiring scared me a bit. Had more than one visit where "TFT down again, let's listen to digital". Lately he's worked through his issues and is very pleased. While the micrometer VTA has some appeal, the digital display reminded of a $5 tool from Harbor Freight. The large dial was also more awkward adjusting than you'd expect and inferior to the dials on other VTA adjusters like those on VPIs or the terrific one on the Technics EPA series that I used to own.   

Someone correct me if I'm wrong, but I thought I read that the Michell arm mentioned is made for them by Jelco, as are a number of other companies' arms. If so, that would make me think that a Jelco branded arm might be a better value...conjecture sure, but perhaps worth consideration. Cheers,