There are several factors here
1. Price you are willing to pay (no point in anyone here listing off primo pickups if you are only willing to pay for stock Duncans/DiMarzios)
2. What exactly do you want from the pickups tonewise
Personally I like Lollar, Fralin, Duncan/Antiquities, and Bareknuckle (for acoustics I love LR Baggs new Lyric system).
I play mostly rock n roll, alternative, indie, folk, blues, classic rock, country, etc. So my type of tone lends more toward the vintage end of the spectrum and I have guitars with P90, PAF style humbuckers, filter trons, DeArmond/Dynasonic, strat singles, tele singles, mini humbuckers, etc.
Having an idea of what your guitar sounds like acoustically and with the stock pickups will help you determine what your new "ideal" pickup should sound like and can give others a good frame of reference when making suggestions. For example if the guitar is really bright and you want to mellow that out we can suggest a particular type of pickup that can help with that.
Honestly while pickups do make a difference it is important to keep in mind it isn't always going to be a night and day difference like the amp you use, etc. And in some guitars some pickups can work wonders while others just don't fit. Throw in personal/subjective opinion and that's why there are soo many options available.
If this is your first forray into swapping pickups check places like Reverb, Ebay, etc if you are comfortable with buying used there are lots of great deals on used pickups that way you aren't shelling out more than you'll get if you decide to flip em later as you test the waters.
Off the regular old shelf though there are a lot of good options depending on the guitar and what you want from DiMarzio and Duncan that won't break the bank.
If it were me just making a general suggestion for good all around humbuckers I'd cast my votes for Lollar Imperials or Fralin's Pure PAF set. I also highly suggest Lollar's Single Coil for Humbucker they are similar to a Duncan Phat Cat (P90 in a humbucker shell) but these bad boys sound killer. The great thing about P90's is they sound great clean and they take dirt exceptionally well so they sound good in just about any application.