If you're used to using a Janome O/L unless you've used the style of Jaguar / Frister Rossman overlockers get the Janome.
It's really going to depend on how you use the features on your machine.
If you engage and disengage the knife for overlocking in the round, you may find the way you have to do this on the Jaguar will be much more cumbersome than you're used to.
If you are used to switching easily between overlocking, rolled hem, narrow and wide stitches on the Janome, then doing the same thing on the Jaguar is different. You have to insert or remove the correct width of stitch tongue to be able to make the different stitches.
You're familiar with a particular style of overlocker so if you're going to switch to another style, doing a test drive on it first is the way to go.