Haven't really been looking at this thread previously as I don't like spiced (or sweetened) rums as I prefer sipping neat to mixing as additives such as sugars and spices hide the true nature of the base Rum, but this seems more of a general Rum thread now (maybe the title could be changed?).
My favourite affordable rum used to be Mount Gay Black Barrel, decently aged in Bourbon casks, it was smooth and naturally sweet and was a great sipping Rum but the price which used to be ~£20 has gone up by over 50% I think due to new ownership wanting to further segment their offerings as Black Barrel was not much more expensive than the regular Mount Gay but was a much better product.
My new affordable favourite is The Duppy Share (Aged) which can regularly be had for ~£22, again it is decently aged to make it a good sipping rum, it lacks the Bourbon notes of Black Barrel but is still naturally sweet and has some character from the blend of Bajan and Jamaican rums where Mount Gay is solely Bajan. I'd really like to try their XO rum one day.
My favourite "special occasion" Rum is Mount Gay XO noticeably smoother than Black Barrel due to the extra aging with a more delicate but still complex flavour profile.
I tried and really liked Diplomatico Reserva Exclusiva but being very much sweetened I think of it more of a liqueur than a Rum.
Notable mentions to the aged Cuban Rums that I've tried (Havana Club 7 / Santiago de Cuba 8) totally different much bolder smoky / tobacco / molasses flavours, but being aged still pleasant enough sippers if you're in the mood for something a bit different or a cigar
The only rum I will drink with a mixer is Wray & Nephew Overproof with Coke, the most memorable taste of my trip to Jamaica.