I have done both
. Though the Technics arm is a major improvement once rewired and shrink wrapped it can be improved on. With a good cart you will be probably be very happy. Its also easy to adjust and set up. I found the Jelco sa-750 a lovely built arm and a nice change to the clarity of my music. Initially fitted with a Ortofon 2m Blue(Excellent cart for the money) it was very happy. Upgraded to a 2M Black and it sounded amazing. Its all down to what you want to spend. Also remember most Jelco arms dont come with the RCA cable so factor that into costs.
Technics SL1210 MK2 fully rebuilt and repainted. Ortofon 2M Black Cart, Isonoe isolation feet , MN bearing and Funk Firm platter upgrade, Oyaide RCA Tone Arm and speaker cables, Jelco SA-750D Tonearm. Oyaide HS-TF Carbon headshell, MCRU Linear External PSU, High Fidelity Crystal glass turntable matt, Blue LED upgrade, Denon AVR-2808CI Amp, Bowers and Wilkins DM602S3 Speakers,
Black Rhodium Jazz power cables for amp and turntable, Firebottle mk2 Phono Stage.