I started with a Gaggia Classic a few years ago and fully modded it with a brass head, PID, flow control, precision baskets and shower screen. I also stripped the boiler and fully insulated it to improve temp stability. Turns out good espresso. Also had a Quick Mill Essence. Beautiful machine with the E61 head but it started to leak after a week and so did the replacement so I backed them. Not what you'd expect from a 2.5k machine. The electrics/wiring internally were similar to their (Italian) sports cars of the 90's, a total joke and not acceptable for this day and age. Couple of years ago I converted to a Londinium spring lever (Vectis). As long as you're into dark to medium/dark roasts at a 1:2 ratio its a total game changer and makes all pump machines taste inferior, even the likes of La Marzocco, Dalla Corte etc. There's literally zero maintainance too apart from replacing the seals once or twice a year depending on usage and can be done in 10 mins. The only mod I have made is I installed a solid state relay to switch on and off the pressure stat therefore taking the current load away from the small contacts. This will greatly increse the life of the stat.
Espresso can only really be as good as the grinder and the understanding of adjustment according to the conditions and beans used. I am currently using a Kinu M47 Classic which is a really sweet manual hand grinder built like a tank and a Fiorenzato F64 Evo. The Evo is a bit of a hidden gem and is used in a lot of Italian cafes. It's pretty noisy and wastes a fair bit of coffee due to purging but the grinds it produces are really really good and with the lever is one hell of a tasty experience. Fine espresso is an art form and the faff that goes into making a small quantity of fluid just makes it more enjoyable, for me anyway.