Pro: South end of the "usable" portion of Barnegat Bay, so lots of "open" protected water; Mariner's Marina is not outrageously priced; marina that specializes in sailboats with plenty of deep water access (especially good for when we move up!
Con: Roughly doubles the drive to/from Avalon compared to Ocean City (turns the trip into at least a 2 hour experience, instead of a "quick" trip); no family/friends in the immediate area; Mariner's Marina looks to be a decent marina, but it isn't exactly scenic.
Pro: Whole area is beautiful; Dillons Creek Marina is in an fantastic location, well maintained, and over all seems very clean and family-friendly; Marina owner is a sailer, and caters toward sailboats; friendly and helpful staff.
Con: farthest away at almost an hour and a half each way; marina is fairly expensive (get what you pay for).
I do know that there are other marinas in Barnegat, but all the ones I've seen that take sailboats are basically on par with Mariner's and I may as well wind up at a marina that favors sailboats. Similarly, I know there are other marinas in Toms River, but if I'm going to go the extra distance, I may as well be in a nice marina, otherwise I may as well be at Mariner's since it's cheaper and closer.
I try not to push too hard toward one place or another. Everyone has to make their own decisions and different things are important to different people.
But here are a couple of more things to think about (like you need more to think about
Your boat is a 1984 (27 years old) and this is your first year with her. Figure there will be unexpected boat projects that will crop up and odd ball parts that you'll need. Make sure there is a good marine store nearby your marina. There's nothing worse than an hour round trip for a $2 part (remember shore traffic). On LBI Morrison's is first rate, near Mariner's it's The Boat Shop on Bay ave in Manahawkin. On Forked River it's Bob's Square Deal or Silver Cloud. Up on Tom's River you're near the West Marine super store in Brick.
You mentioned Mariner's. There are some pros and cons. We were there one season and moved up to Forked River. On the plus side Richie and his family are really nice people and Rich is a solid mechanic. I've heard only good reviews of his work. There's a group of sailors who've been there for a long time who are really friendly.
On the down side the marina was VERY buggy when we were there. Rich has a business building barges as well as running the marina, and it felt like that was his priority and you won't want to be in the marina during the week with the noise. A 25' boat will probably be on the outside. The boat wakes out there are just awful, and where the marina is situated the wind can really howl across the slips. Docking can be interesting until you get the hang of docking in a crosswind (not a recipe for marital bliss). Finally there's nothing that's walking distance from the marina and your restaurant choices are limited - unless you drive up to Forked River.
We moved 15 minutes up the bay to Forked River and are really glad we did. We're at Southwinds (protected, no bugs), recently remodeled rest rooms and walking distance to the restaurant at Southwinds or the Captains Inn.
Less expensive options would be Rick's, Tall Oaks, the State Marina or a slip at the Inn at River's Edge B&B.
Tall Oaks has the advantage of access to the pool at Silver Cloud next door (same owners). Lots of additional restaurants on rt 9, a WaWa, ice cream shop, Shop Rite, etc. Boat parts are never more than 10 minutes away.
The problem if you go south onto Little Egg Bay is you'll want to be on the mainland side for easier access by car (compared to LBI traffic); but the greenheads are murder through that area.
Hope this helps,