I am a Pro-ject guy having had a RM 1.3 and now an RM 5.1 SE. Never had a Rega so I cannot do a direct comparison. I can only say I like the Pro-jects very much, nver had any roblems with either table I've owned, and feel they are outstanding values for the money.
That being said, if you budget is $300 for a table & arm without a cartridge, then look at the new Pro-ject Carbon at $400 with a cartridge! It is a souped up version of their already best selling Debut III having the following upgrades - 8.6" full Carbon Fiber Arm, RCA jacks for your choice of cable, full 12" platter and factory equipped with the Ortofon 2M Red, a $100 cartridge that I believe was already recommended in this thread. In the $400 range for a table & a cartridge, Pro-ject appears to have a winner here. Hope this helps.
Marantz PM15S2 LE, Oppo BDP-103, Simaudio Moon 100D DAC
VPI Traveler V2 with an Ortofon Rondo Blue and Simaudio Moon 110LP, Technics SL-1400 with an Audio Technica AT-14sa and Pro-ject Phono Box S
Dynaudio Focus 260's, Rel T-1 and a Panasonic TC-P54S1.