What cartridge to use....Rega RB25 Structural Mod

I have a Rega RB250 with the JA Michell structural mod and Incognito rewire mounted on an Acoustic Signature Final Tool. I am currently using a Koetsu Red with very good results. I am looking for something better. Aren't we all?? As you may or may not know, the Michell mod allows use of just about any cartridge made. There are 2 different counterweights. One for cartridges with a weight of 3 to 6 grams and another for cartridges with weights from 6-13 grams. The RB250 has an effective mass of 11 grams. So, with this in mind, what do you think. I am trying to stay within the $1,000.00 range, new or used. I have some cartridges in mind. The Dynavector DRT XV-1, XX-1, XX-2, ZYX Fuji R100 FS, Benz Micro LO.4, Lyra Helikon and the Ortofon Jubilee are some of the choices thus far. I have not listened to any of the above cartridges. I am going on reviews from this site and some of the professional reviews I have read. Please let me know if you've had any experience with similar setups or if you have any recommendations/suggestions regarding other cartridges I haven't mentioned. Also, I need to purchase a cartridge alignment tool. Any suggestions on tools under $50.00 would be great!!

Thank You
Jeff