This is almost an unanswerable question, as it really depends on the individual, the budget, and multifarious other factors, such as your willingness to let coffee equipment take over your kitchen. If you want to drink espresso and have a budget that is less than several hundred Pounds, then the Nespresso machine and Colonna pods are your best options. If you like espresso based milk drinks, budget a bit more for a Nespresso machine with a decent steamer (don’t bother with the machines that have integrated milk pichers that auto-steam the milk – they don’t really work). Alternatively, buy a base level Nespresso machine and a separate steamer.
For filter coffee, the starting point would be a decent hand grinder, such as those produced by Porlex. Electric grinders only produce better coffee than hand grinders at much higher budget levels (as you’re paying much more for the electrics, rather than any improvement in grinding quality until you ‘re well into the triple figure cost level). Pair this with an Aeropress, which is the easiest and most consistent way to make filter coffee and you’re well on your way to making great coffee. Avoid blade grinders and electric grinders that are under the £100 mark.
If your budget extends to around £500 you can get something like a Gaggia Classic and a decent used commercial grinder. The Mazzer Super Jolly is popular and can be picked up for around the £200 mark used. Anfim Caimanos are also good at this level, or if you can stretch a bit further, the Super Caimano can be had used for around £300 and is good enough to have been used to win the World Barista Championship on several occasions. Remember that the grinder makes more difference to the taste and quality of the espresso than the machine.
Beyond this there are various machines from the likes of La Spaziale, La Marzocco and Sage. Look for dual boilers (enabling you to steam milk and extract espresso at the same time), PID control of the brew temperature (enables greater consistency) and commercial style groupheads. Don’t be tempted to purchase a used commercial machine, unless you’re willing to a) use up all your kitchen space b) have it wired to a dedicated 32amp power source c) enter an ever spriralling search for the perfect water/grinder/tamper/etc (you get the idea).
Remember that making a few coffees on a proper machine generates a significant amount of mess; if you’re OCD about your house, Colonna pods and a Nespresso machine will be friendlier companions.