The way to get the best possible gloss is to first apply a high quality sealant and then, on top of the sealant, apply a high quality carnuaba wax. The sealant will provide protection and a candy-like gloss. The carnuaba wax, which is not as durable or as long lasting as a sealant, provides a warm glow that you just can't get from a sealant. So instead of choosing between a sealant or wax, use both! You always apply the sealant first and then, after it cures, you apply the carnuaba wax. Here is an awesome sealant / wax combo:
Jescar Powerlock (sealant) topped with Collinite 845 Insullator Wax
If you are going to apply a Carnuaba wax, I personally think the Collinite family of waxes is the best on the market. It is one of the most durable carnuaba waxes available and will last 2 to 3 times as long as other carnuaba waxes. I also LOVE Collinite 915 Marque D' Elegance. It is not quite as durable as the 845, but it does have the highest concentration of carnuaba in any Collinite wax. So if you are going for the warmest, deepest shine and gloss, 915 is amazing. The 845 is a close second in terms of gloss, but it will last a month or two longer than the 915.
Another option, which is not commonly known, is this sealant which I came across reading Autogeek.net forums:
Four Star Ultimate Paint Protection Sealant
The unique thing about this sealant is that many people feel it is one of the few sealants to actually offer the warmth and shine of a carnuaba wax. Here is a description of the sealant from Autogeek.net:
"Four Star Ultimate Paint Protection delivers a high gloss shine in an easy-to-apply, liquid paint sealant. The synthetic sealant with Polycharger polymers offers months of protection and a depth of shine similar to a carnauba wax."
I have used these products and the end results are amazing. That said, you had also asked for something that is super easy to apply. The above products are traditional wipe on, allow to dry/haze, and then buff off. Although not super hard to use, they are not as easy as say a spray-on sealant. If you want the easiest to apply products, I would go with a spray-on such as:
Opti-coat Hyper Seal - a synthetic sealant from the makers of ONR. Hyper Seal is in their professional line Opti-coat and can only be purchased from the Opti-coat website. It is a ceramic-infused spray on sealant and it is amazing stuff. This costs about $40 a bottle, but a little goes a long way and the bottle should last you over a year.
Turtle Wax Seal and Shine - before you laugh at the idea of a Turtle Wax sealant, this sealant is blowing people away, especially for its value. It does not contain ceramic, but it is a super durable synthetic sealant that is infused with carnuaba wax. So it is a super easy, spray-on way to apply both a sealant and carnuaba wax. I have personally used this on my wife's Honda every 3 or 4 months and it is awesome. Especially at $7 a bottle.
Finally, to maintain gloss and shine, you can use a spray on gloss enhancing spray after each wash. Others have mentioned Bead Maker. Personally, I am not a huge fan of Bead Maker. Yes, its shine and gloss are amazing, but it is not durable at all. If you are taking your car out for a night on the town and just want to apply something to make the car shine like crazy, then Bead Maker would be great. But I also value protection. If a bird dropping lands on my paint, I want a product to protect it and Bead Maker really falls short in protection and durability, IMO.
Here are two alternatives to Bead Maker:
1) Technicians Choice Ceramic Detail Spray - this is a ceramic infused detail spray that I love to use after each wash. I posted a recent review of it and nicknamed it a ceramic Bead Maker. You get the slickness and gloss of Bead Maker but, due in part to the ceramic in it, you also get amazing protection that is much more durable than Bead Maker.
2) Meguiars D156 Synthetic Spray Wax - Super easy to apply spray wax that adds shine, gloss, and a bit more protection. Can be used as a drying aid or on dry paint.
In case you can't tell, this is something I am really into so if you want to ask me any questions, feel free to post here or PM me.