Tonearm Advice Needed

I would appreciate some advice on selecting a tonearm.  While new to the forum - this is my first post, I have spent quite a bit of time reading on a number of topics over the past couple of years, or so.  And, while I've had several systems composed of separates, I have allowed myself to become a little stagnant over the years.  So I have "some" knowledge, but I'm nowhere near sophisticated.

I have a couple of turntables, but I purchased another one some time ago. I plan to use it with a new system I am in the process of assembling. The turntable is a first year production TD124 (1) in great shape I bought at a pretty fair price. I did set it up with a mid-level tonearm with a MM cartridge and it was somewhat impressive. Thus, I was encouraged to improve the sound with a nice arm.

Before knowing as much as I needed to know, I put the proverbial cart before the horse a couple of years ago. I latched on to an SME 3009R still sealed in the original packaging.  I've not taken it from the sealed wrapping, since I later thought I may need a lower mass arm for an MC cart, such as an AT Art 9.  I'm considering the similar style SME M3-9R.  I could depart from the iconic style, I suppose.  But the new model may be sufficient - I'm not really sure.  The system I'm putting together so far consists of a Pass X250, Pass X1.  Phono Pre may end up being Pass as well. At the present, the phono is an ifi 2.  I've tentatively set the tonearm budget at around 2K, thinking I could sell the NOS SME to at least partially fund the new arm. I not quite comfortable with a used tonearm.  I'm not married to the whole TD124 thing, but I'm hoping that for the cost of the table and arm I can obtain very high quality sound for the money.  I'm budgeting for new speakers, having lived with 4311's and AR10Pi's for a long, long time. I listen to all genres of music.