Help me choose a mono cartridge

The standard Ortofon 2M Mono runs about $350, and being MM, is high output. The AT-33MONO is low output. However, the AT-MONO3/LP is very similar but with relatively high output--1.2mV. I have that one and it doesn't need a step-up transformer.

The Ortofon 2M Mono, AT-33MONO, and AT-MONO3/LP all have spherical styli.

I know it's below the budget range under discussion, but I got my AT-MONO3/LP from Amazon for $112.65. It's a no-brainer at that price.

I really like the way this cartridge improves mono playback. Not only did it amp up the transparency and dynamics of my 2014 Beatles Mono LPs, it makes thrift shop mono pressings from the '50s and '60s sound excellent. Several were unplayably noisy with a stereo pickup, but are really quiet with the AT-MONO3/LP.

You will find a wide price range of mono carts on Acoustic Sounds, including Koetsu, Benz Ace, Denon, Shelter, Grado, Ortofon 2m and Quintet Mono versions, and Lyra Kleos.

Koetsu Black Mono will serve a musical reproduction with those records

Rshak, I was interested to read that you contemplate replacing a Helikon Mono with a 2M Mono SE Ortofon.  Would you care to amplify on the rationale for that?  I ask only because the Helikon Mono is much more expensive and has been highly praised. 

lewm - - Sorry if I was unclear in my post:  I said I was thinking of replacing the Helikon mono with an Ortofon mono but wasn't sure which one would be best.  I would not go with the 2M but am looking at either the Cadenza or Quintet. Or . . . perhaps I should get the Helikon repaired.

Trying to get a handle on conical vs elliptical vs fine line and match all that up with my mono collection (1950's originals up to current reissues) is a bit daunting.  Then there's the "best bang for the buck" angle to take into account.  

I agree that all those are issues associated with choosing a mono cartridge or even just choosing to buy one at all.