Vector, for sure...
The top 3 multifunction hardware most commonly used are Furuno, Raymarine, and Garmin, although the more expensive Northstar is popular in expensive yachts. All three offer radar overlay capability with the use of a fluxgate compass. This feature, which shows radar returns on the chart display as well as on a regular radar display, is great for identifying returns. They also offer display of sounder/fishfinder information.The top 3 cartography products for these are Navionics, C-Map, and BlueChart (Garmin). Furuno gives you a one-time up-front choice of Navionics or C-Map, Raymarine uses Navionics these days. Garmin uses Garmin BlueCharts. All three cartography products are vector, and are good, but some may have better coverage in particular remote areas than others. For example, only C-Map has detailed coverage of Guam. All three have websites that show their coverage, and you should take a look to ensure the coverage is adequate for the area you'll be in.The government is in the process of developing vector, standards-based Electronic Navigational Charts (ENCs), which will probably eventually become the standard and hurt sales of the proprietary charts, since they are free to the public. While the Version 2 offer decent coverage of coastal areas, many areas such as the Great Lakes are still at Version 1 and not ready for primetime. You can't just use a small scale chart standalone, like you can a paper chart. It has a number of "holes" in it, that are covered by larger scale charts, and this is true all the way down to very large scale harbor charts, so you have to make sure to get all the charts. Perhaps one day major hardware vendors will switch to these, but for now viewing them requires a PC at the nav table, or a PPC in a waterproof cover at the helm. IMHO, the software for viewing these charts is really crude at this stage.Getting back to the big three, there's considerable difference in the software that views the radar and charts. Garmin has always been praised for its ease of use, being like the Apple Macintosh of chartplotters. Garmin owners are very fond of them, and report good customer service when needed, but all of the big three get good reports there. All three have their owners and installation manuals downloadable as PDF files from the company websites. I'd strongly advise you to download them, learn their operation, and only then get some hands-on time with them at the store.