A far as I'm concerned, if you like turn on and go detectors, the tesoro would be the better of the two, the tesoros also have excellent recovery times over multiple targets vs the coinmaster. The Coinmaster is noted for its slow recovery times, which is not what you want in trashy areas, the only real advantage the coinmaster has is its weatherproof control box, 3 tone id and digital screen, but that wouldn't be a final selling point for me. Try and find a bad review for the Silver, very few, but plenty of satisfied owners that love to let you know how good they are. The Tesoro also has more options for coil upgrades as well, and only requires one 9 volt battery for operation vs coinmaster requiring two (9v batteries can become expensive)
Don't rule out the Compadre either as a first detector, they also rate well amongst users, the only downside is a fixed coil, small coil (great for target separation, but not for covering ground), and lack of sensitivity control. You get a choice of a 5.75" fixed coil, or a larger 8" fixed coil for the Compadre, the smaller coil being better for getting close to metal objects in tot lots and better seperation of targets in trashy areas. The 8" coil would be the better choice of the two for me, a bit better coverage in park or beach areas, whilst still small enough for good target seperation. The Compadre is nice and cheap at around $200. The Ace and Silver Umax are similarly priced at around the $350 mark.
The Ace 250 has great features for its price point, including selectable notching (not on coinmaster), light weight, very economic on 4AA batteries, and an excellent range of coils from both garrett and aftermarket suppliers. As mentioned, downside is lack of true all-metal mode, and not really the best recovery time. Some people don't like the bell tones it gives off over $1 & $2 coins, but I personally like that feature.
No bottom line VLF detector will work perfectly on the beach in wet sand, usually requiring a drop in sensitivity for quiet operation, but they do well in dry sand.
Google Tesoro Silve Umax and Compadre, and you will quickly find all the good feedback, get feedback on the Coinmaster, and you'l find some people like it, whilst others would prefer to wrap it around the closest tree.