In most parts of Britain, FTA satellite from 28 degrees east (e.g. Freesat) is able to deliver overall more broadcast content than DTT/Freeview, and more in HD too - there's no more room for Freeview to launch HD channels unless at least one more of the current DVB-T multiplexes converts to DVB-T2 and there appears to be no sign of that forthcoming - the time to have done that would have been around the 700 MHz clearances, but it looks like outside of the current HD channels ( and the BBC SD channels that have an otherwise reasonable bit rate) Freeview is destined to be a platform for low-bit rate SD channels for the foreseeable future. AFAIK the only service broadcasting on Freeview that isn't available on satellite at 28E is WildEarth TV.
In saying that, I still have terrestrial aerials as I need them to receive DTT services from the Republic of Ireland (Saorview) as they carry services that aren't FTA on 28E, including RTÉ 1 & 2 in HD as well as the Virgin Media stations. I could use Saorsat on the Ka Band at 9E, but it doesn't carry the Virgin Media channels (useful for European club & international soccer - yes they're only SD on Saorview but they're better than nothing) nor TG4 in HD either.
Ultimately your needs may very - it might depend on factors like how easy is it to run another cable or two from a multi-output LNB to a receiver in a bedroom, study etc. if you're not using a multiswitch, how easy terrestrial signals are to pick up locally (can you get away with a set-top style aerial in the room?) and so on.
I suppose the only guess is how long broadcasts on each platform, both satellite & terrestrial, are likely to continue? Terrestrial has two iff-ish dates of 2030 (currently the minimum guarantee under ITU regs, to be discussed at a WRC at Dubai next month if I'm right) & 2034 (when the licences are due to expire for the six national multiplexes). For satellite, the big problem is the requirement of a UK spot beam to allow for the main UK broadcasters like the BBC, ITV etc. to keep broadcasts FTA. Astra 2G is the youngest satellite up there & it's expected mission lifetime is scheduled to end around 2030, but of course this will be dependant or several factors inc. the health of the birds in orbit, wherever another satellite (SES or otherwise) could be brought in to fill in, wherever we might get new direct replacement birds (would seem unlikely at this point, especially if Sky ultimately decide to end DVB-S(2) services by 2030), or that an MEV might be put into place that could keep one or more of Astra 2E/F/G going for a few more years beyond their expected life.