Jannsen (J&J just supplies the lobbyists) seems to be about the same thing as the AstraZeneca gene therapy platform insofar as it is an adenovirus engineered with some spliced in designer DNA (NOT mRNA). The DNA payload is probably transported into the nucleus as is the case for AstraZeneca, but they are very very hazy about this in their marketing material. In fact they bend over backward to not even mention 'DNA'.
Another candidate which I find genuinely promising would be Novavax. This is a relatively old-school sub-unit vaccine with their secret sauce being a new 'nanoparticle' adjuvant they've been working on. If the adjuvant can work without inducing autoimmunity or other problems, that's a genuine step forward which could increase the dismal safety profile of a lot of vaccines. That would be a great thing. As with most 'anti-vaxxers', I actually don't have anything against vaccines in general. I just wish them to be safer and used for the stated purpose.
It is deliberately hidden, but all of these 'covid vaccines' are WILDLY different things from one another. It appears to me that a fairly big part of the covid-19 hoax was to open the doors to the pharmaceutical companies to try out their ideas on the peeps without all of the expense and hassles of doing actual safety trials. Mostly they are jumping on the chance to experiment with their gene therapy work.