Hi Mal!
First of all, welcome to the site! I'm glad to hear that you and your buddy are looking to get back into the game. As far as which sets to look into, your answers will likely be as varied as the people who give them, but here's some humble advice from having been in a similar situation.
My "best-bang-for-your-buck" tips:
1- Do a couple of quick searches to see which cards/combos are out there which you might like.
I like to do searches in databases like the one here at TLHH, and have had luck at retail sites like ccg-singles.com , too. A search for "Aragorn," "Gandalf," "moria orc," etc., will pull up all cards that have the words in the title or game text. This can help you see which cards might be helpful for your strategy - you might think of a few fresh ideas in the process. The "Lothlorien" section of this site might inspire a few deck/combo ideas if you're looking for a few new ideas to run with, too.
http://lotrtcgwiki.com/forums/index.php/board,3.0.html2- Play-test the cards on GEMP
If you haven't tried it out already, I'd highly recommend building a deck on GEMP - it's a free online version of the game that lets you play with every card ever made, and I find it very user-friendly (did I mention that it's free? haha). The huge perk you'll find here is being able to see if you're happy with how cards work together - a free way to find out how well ideas do/don't work out before you buy real cards (this has saved me money!).
To play:
http://www.gempukku.com/gemp-lotr/ Tutorial:
http://www.youtube.com/watch?v=azvdgl4LScs (since you've played before, the first 5-7 min. should give you a handle on how to use the site)
If you play on GEMP, I'd say to start off playing Fellowship Block (sets 1-3), Towers Block (4-6), or Towers Standard (1-6) to avoid mismatches against cards from later sets.
3- Buy based on the sets you find most useful
After play-testing your decks (or at least after searching to see what cards are out there), you should have a better idea of what sets will be most rewarding for you. If you like how your virtual deck works, take note of which set(S) most of your cards are from, and that can better guide you on where to put money down to buy boosters or single cards.
A word on sets:
Booster boxes are a fun way of diversifying your play options, but if you have a few favorite characters and cultures you like to play with, I'd definitely consider looking into buying singles, too (can save money and aggravation if your Moria box doesn't produce a Balrog). If you choose a booster box but have a few random cards that aren't available in the set, I've found it pretty easy to find most cards as singles from various shops online.
Buying into a base set (Fellowship and Towers, sets 1 and 4) have a lot of great options, and offer a lot of variety - both a plus and a minus. There are lots of great cards in each of the sets. However, with more cards (and cultures in Towers), you may find yourself with singles that don't see much use.
I'm a huge fan of buying my cards as singles, so my set evals should be taken with a grain (shaker?) of salt.
Fellowship (1)- great base set; a "must" for Uruks (Lurtz, Troop, Lieutenant,
Lurtz's Battle Cry), and very good core for Moria. With rares like
Aragorn's Bow,
Glamdring, and
Blade of Gondor, your fellowship can get a nice boost, too. Provides a good core for the free peoples culture A top pick.
Mines of Moria (2) and Realms (3)- I like some singles in here (Balrog,
Gandalf's Staff, and
Mithril Coat in Mines of Moria, and
Long-Knives of Legolas,
Gondor Bowmen, and Isengard orcs in Realms to name a few), but I was satisfied in getting these as single cards without buying whole boxes.
Towers (4)- Another great base set. Great for your Faramir and ring-bound rangers (
Faramir's Bow,
Faramir's Cloak,
Boromir My Brother, Ranger Bow,
Ancient Roads, etc). Rohan is a great addition, and can be a lot of fun. Lots of Uruks to blend with what you have, and offers new strategy options (site control, Uruk archery, Uruk trackers are a personal favorite). Introduces Dunland, Gollum, and Raiders. Another top pick.
Helm's Deep (5) and Ents of Fangorn (6)-
Warg Riders and Uruk berserkers from Helm's Deep can be fun, and I enjoy the ents (some of which you may have). As with Mines and Realms, rounding out with individual cards from these sets may serve you better than a full box.
I hope this was helpful - let me know how things go for you, and happy gaming.
All the best to you!
P.S.- If you want to play on GEMP, my name is Dunadan325.