What should I buy for my drop shot combo ? Reel ?

Any decent 2000/2500 size reel.

Rod I like is my 6'10" (pre-Trigon) Mojo Bass ML/XF

My setup is 7'  F/ML with a 2000 spinning reel. Usually will run braid10-15# with FC leader6-12#.

A  7’ ML spinning rod with a 2500 reel is what I like . 

I throw it on Shimano Sierra 2500 and Mojo Bass ML- XF.

15# braid 8# Sunline flouro leader.

2000 sized spinning reel with anti-reverse switch...

There a couple of features I like in my dropshot reels.  First is a larger spool.  This aids in castability, reduced line twist and a larger drag washer surface.  You can however get a 3000 size spool in a compact body.  Any of the 3000 Daiwa LT models are an example.  A smooth drag is a must.  Light weight is another factor.  A faster ratio helps in getting line in quickly for the next cast.   Finally, a braid friendly spool.  Happy shopping.

Title says reel but you asked about a combo so here goes...I throw a texas rigged drop shot with either a 6" worm or a 4" shad on it a lot and have tried a lot of different options. My current setup is a 610mlxf legend xtreme w/ a 2500 vanford. Good combo but I also have a couple of adrena spinning rods and for the money and in terms of overall value I'd probably opt for a 7'2 ml f adrena with a 2500 vanford on it. Pretty sure you will be able to catch some fish w/ that setup and a very good option in terms of overall value.

On the other hand if you can find the legend xtreme on sale it is an awesome rod for this sort of thing and they have a 6'10" and a 7'3" and they come with a great warranty too.

Aside from that I'd check to make sure how you like to hold a spinning rod lines up with the one you are looking at. Most have foregrips these days which I'm not a fan of but if you prefer to go that route there are plenty of good options out there.

Either way the vanford 2500 would be my first choice for a reel and there's a lot of distance between that one and the runner up.

I use both a 3000 Vanford (15# braid w/ 10# leader) on a 7’ M/f Edge rod and a 2500 Vanford (10# braid w/6# leader) on a 6’6” ML/f IMX G Loomis rod.

The 3000 gets the bulk of the 5” and up dropshot/wacky/underspin work while the 2500 gets the wacky/dropshot/shakeyhead but in finesse sizes.

Depending on what water and where I fish determines which one is in my hand at any given time.

@gim can tell ya, he’s all about that tactic, kinda like me. 😉

What's you budget and then I can make some solid recommendations.

That said, size matters less than my preference is a low gear ratio. Size and weight are based on balancing the rod. Most DS rods are under 7' so something lighter is usually recommended. I use a 7'6" flyssa for deep drop-shotting, hair jigs, small paddle tail swimbaits, etc. I use a double handled Certate that I got from Japan. Its a compact 2500. For most of my DS, I use a XX whipsnake with a 2500shg twinpower.Some of the Diawas are even lighter. Some feature a finess or compact body and a super shallow spool expecting you to use PE and a leader.

I have struggled with finding a dropshot combo I really like.

My current two setups are ML/F Phenix Feather spinning rods. I originally tried a Vanford and a Tatula LT on them, but those rods are so light, especially through what little handle they have, that they feel a little tip heavy. I found a little heavier Stradic 2500 balances them out nicely.

The other thing I found I like about them is the hook keeper at the butt of the rod, because I can hook my weight on it and it helps maintain the line without the weight swinging around.

If I nose hook my bait so the hook isn't exposed, and catch the weight on the hook keeper at the base, I can twist the line and not have a mess when the rods are stored in the locker.

Like the last poster said, weight and balance is important in dropshotting. You are going to be holding your rod horizontally and shaking it a lot so, get a reel this is light/heavy enough and that will work with your rod to let you do that comfortably ALL DAY.

A really good drag helps a lot also.