I have had both Optima red top and yellow top batteries, they are great. I currently have a yellow top in the Yukon that was previously powering our camper. I had been buying Optima batteries from Sams club, but they switched and now carry duracell instead. That is fine with me, they are priced much lower than optima. I did some research and found that the duracell agm batteries are made by Deka/East Penn mfg. - which is one of the best battery makers out there. I have a duracell agm in both my Pacifica and my wifes Town&country van, and two duracell deep cycle agm's in my camper.
Agm batteries do not corrode expensive cables/terminals like flooded batteries, last longer, hold a charge much longer, and can be mounted in any position (my 2 camper batteries I have mounted sideways). I clean the terminals when replacing the battery, put a coating of terminal protector on, and have not had any terminal corrosion since.
Most of the guys on the camper forums are using flooded batteries that require constant maintenance, checking/filling water level in each cell, testing with a hygrometer, checking charge level, etc weekly or monthly. I switched to agm and will not go back! I may have less reserve capacity, but the low maintenance/durability is worth it to me.
A deep cycle battery can be discharged (to a point) again and again without damage. A regular battery cannot, but usually will have higher cold cranking amps and/or reserve capacity. So, if you use your battery to run accessories without the engine running-and do not live in the north, you should get a deep cycle. Deep cycle batteries cost more, so only get one if you need it.
I have found that the price of the duracell agm's at sams club is only slightly higher than the flooded batteries from my local auto parts chains and walmart.
On the alternator, I do not know which brand to recommend, but I look for a high output one that will produce at least 100 amps at engine idle. Almost all standard ones only output their rated amperage at 1500 rpm or more. That means on short trips or in-town/stop and go traffic the battery is not getting fully recharged. Add extreme high or low outside temps(running hvac, wipers, or other accessories ), there is a good chance of being stranded with a no start due to a dead battery. Been there, don't want to do it again!
EDIT: FWIW, I live in Maine and have used optima yellow top batteries in a 1998 Jeep wrangler 6 cylinder and never had any problems starting it in the cold.
