Some background and comment on points raised by others:
The flights I looked at were in just over 2 weeks time, and booked 3 weeks ago. The choice was
Loganair ex LCY dep 1830 arr 2005 £174pp inc bag - £522
easyJet ex LGW dep 1915 arr 2035 £33pp ex bag, £54 inc bag say £162
Pre Covid I flew to London at between 12 and 24 times a year. I've been flying IOM/LCY since the original BE operated their BHD/IOM/LCY service over 20 years ago. I flew IOM?LHR and then IOM/LGW with Manx then BA Connect. I flew IOM/LGW with the next generation BE until they pulled out due to LGW's price increases which favoured larger aircraft. I flew to City on EuroManx, Aer Arran and even VLM. BA's services using Eastern and Loganair metal became my service of choice. I am an LCY fan. I have probably flown no more than 10 returns with easyJet to 2020.
Thameslink gets me from LGW to EC1 in 40 minutes for £16 contactless (saves a queue) and back for £8.40 off peak. Tube and DLR used to get me to/from LCY in 40 minutes for £2.70; more now I guess. Loganair's Saab 2000 was quick to LCY until the changed airspace routing, when it was became 1hour 20 minutes. Loganair's ATR42 was much slower, taking up to an hour and 40 minutes. My flights with them in Feb/Mar 2020 pre Covid were quicker thanks to ATC giving them a direct routing. Return flights were just over an hour. easyJet are usually an hour to LGW; an hour 10 back. At LCY bussing to/from the early morning and the evening flight was the norm. Thus far easyJet manage to use the Gate 55 jetways but I've only used the 9.55 easyJet flight. The morning flight has been ahead or close to scheduled time of 1110 and with no hold baggage I can to get the 1146 Cambridge Thameslink service. Getting into LGW after 10pm doesn't appeal at all.
So real travel times for both routes are similar, although arriving at LCY on a mid day flight will usually get me into town slightly quicker and at a lower surface price.
I'm not an easyJet cheerleader. I started using them because they were the only option post Covid. I don't particularly like Gatwick. And if anything blocks the track between East Croyden and Gatwick you are stuffed. I'm not driven solely by price. But to pay £360 more to Loganair than I have to for the same service (and bear in mind we are hand baggage only so the actual extra payable was £421) seems crazy.
Let's see how this plays out.