Best Ortofon?

If you can swing the extra $250, buy a P2 instead with Ortofon 2M red -- especially if you think you'll want to upgrade the counterweight, subplatter and platter later. Much more flexibility this way and the stock P2 will outgun a tweaked P1 right out of the box.

The glass platter will make a difference in terms of definition, detail and pitch stability on the P1 or P2. You might also try an acrylic platter, just be sure it weighs the same as the OEM Rega version. BritAudio sells an acrylic platter for only $59 but it's not quite as heavy as the more expensive ones from other manufacturers. That said, if you're on a budget, it's cheaper than a Rega glass platter and way cheaper than expensive acrylics.

I agree with Kirkus on the "20" stylus if that's our only option. However, the Ortofon OM series has effectively been replaced by the new and much improved 2M series, which was designed specifically with Rega tonearms in mind (as you can see from the picture linked below). Instead of paying $100 for a "20" stylus, I would strongly suggest you spend the same money on the 2M Red cartridge. It is a much better compliance match than the 5E with 20 stylus.

Unfortunately, the P1 has a slightly different design than the other Rega arms, so you won't be able to take advantage of the easy installation offered by the 2M. (You can rough it in by eyeballing a mark that sits where the third screw would be in a Rega three-point mount cartridge.) However, since the P1 shares a lot of the design details, it will still make for a very good interface.

Bottom line: on a budget table like the P1, you don't want to go crazy with expensive tweaks. You could easily spend more money than it would cost to trade up to a P2, which is a superior machine with much greater upgrade possibilities.

If you can swing the extra $250, buy a P2 with Ortofon 2M red -- especially if you think you'll want to upgrade the counterweight, subplatter and platter later.

2M literature:
https://system.netsuite.com/core/media/media.nl?id=11889&c=ACCT106601&h=55e52a54d41542df9f13&_xt=.pdf&ck=P9EcKSE1Ad9kWUnS&vid=P9EcKewSAcI0jLOQ&cktime=79137

Thanks very much for the detailed and helpful response. So I want to throw one more option in there: What about the Rega Bias 2 vs the Ortofon 2M Red vs the Ortofon OM20? I though that, since I'm using the Rega P1 and Fono pre, maybe it would make sense to consider the Rega cartridge as well.

I owned the Elys, which is the next step up from the Bias, and found it rather dry and dull. I think most people tend to be disappointed in Rega cartridges with the exception of the Exact, which is around $700 now. Also, bear in mind that Rega cartridges do not have user replaceable styli. When the stylus goes, you need to send it out to be professionally re-tipped or exchange it for a new one. If you're new to analog, and not yet comfortable mounting and aligning a phono cartridge, this could be a big negative.

The OM20 is a nice cartridge but it is basically discontinued. The OMN series dates back to the early 1980s and was really designed for the low mass arms of that era. The 2M Red is a more advanced overall design that is a far better match with the Rega arm. The Rega Fono should work fine with it. I guess you might say that the OM20 is more 'listenable' but it leaves me wanting more.

If you find a dealer that sells both Rega and Ortofon, you might be able to negotiate a slight package discount -- maybe 10% -- by buying both at the same time, and as a bonus, they will mount the cartridge for you. I would try Bess at Music Direct, if he's still there, assuming you don't have a dealer in your area.

When the 2M Red stylus wears out, you can always upgrade to the Blue stylus unit as it is interchangeable. You may not want to.

So does the 2M Red mount easily to the P1's tonearm? BTW, I'm pretty handy, so if the dimensions are good, I can probably do a good job. Thanks again.

Any cartridge should mount easily on that arm. You should have no problem at all. But, again, if your dealer sells both brands he should do it for you at no extra charge.