The overly popular choice in 7th edition, the new Savage Orc Boar Boyz received two solid upgrades in the latest version of their rules: the new choppa rule and a drop in point cost. A minimum unit comes in at slightly more than a hundred points, give or take a little depending on your unit upgrades, which is a fair price for them. It will make for a surprisingly hard hitting unit that, although they lack a little in armor saves, should almost always dish out more damage if flanking a foe that's fighting your infantry, than they surrender in wounds back.
In my opinion, considering that the point cost is the same for both, you should always equip your Savage Orc Boar Boyz with spears in order to take advantage of the extra strength rule. With the added strength bonus of first the choppa rule and the mounted with spear rule, your Savage Orc will suddenly not be an inferior fighter to their mount on the charge (like they used to be) and instead both boar and rider will dish out a total of 3 S5. This is almost always preferable, compared to the 1 S5 and 3 S4 attacks of an additional handweapon, when you consider what you should be going up against. Use your Boar Riders to either tackle Monsters or to turn the tide in favour of your infantry by ramming in a flank charge on nasty enemy infantry. Not to mention that the spear upgrade allows you to bring a shield for extra protection. The extra attack of an additional handweapon is fine when fighting goblin-like troops in large, steadfast units, but those are units that your cavalry should be staying clear of anyway. Let your footslogging Savages keep their additional handweapon and make sure that when your cavalry Savages strike, the enemy will feel the sting.
Given that Savage Orc Boar Boyz come in with an armor save equal to a Wolf Rider, with the added bonus of the 6+ warpaint, with the same toughness of a regular orc, they make for a fragile unit that, although they hit hard, will be taken out quite easily. Since they're fairly expensive on a point per model scale, the correct way to counter this is not by buying even more of them for a monster unit (for some reason all White Dwarf pictures show units of at least 10), but rather to keep them small and cheap. This becomes even more true when you consider the strong point of the unit itself; plenty of hard hitting attacks on the charge. A Savage Boar Boy is a fierce fighter up close, but if you put one in the second rank of your unit, suddenly you'll lose out on your frenzied attack, and your mount doesn't get to strike either. This is normally not an issue for horse cavalry, such as those from the Empire knights who have excellent armor saves to protect those extra bodies in the back and neither will lose out on attacks. For Savages riding one of the best fighting war beasts in the game without a decent armor save, putting guys in the back is just not a cost effective way of equipping your army. In all almost all cases, you're better off separating those 10 models into two units.
Unit size: 5-7 makes for good units and is usually the most you can get into base contact with an enemy unless charging an extremely deep steadfast unit. 5 of them makes for a cheap and expendable, yet hard hitting unit that can turn a battle in your favour, while 7 will give you an even more devastating charge and a few more bodies to keep your effectiveness up through multiple battles, as well as allowing you to add the +1 to the Waaaagh even if one or two of your riders have taken a crossbow bolt in the face while charging into combat.
Equipment: Spears are a mandatory choice for your boar riders and indeed anything mounted in your army, while additonal handweapons are better off given to your footsloggers. Shields add another armor save to your fairly unprotected units for a cheap, but since the boar riders will be relatively fragile anyway, it's an upgrade you might end up ditching in favour of something else.
Command options: Musicians should be considered a given for a unit that employs so much speed compared to the footsloggers, as it allows you to swift reform into the enemy flank if required. Standard Bearers are usually only worth it if you're interested in a magic banner and can expand on the use of the Savage Orc Boar Boyz, otherwise you're better off getting shields or something completely different elsewhere.
Magic Banners: There are a few magic banners out there that can be good to equip your Savage riders with. Banner of Swiftness makes your boars run as swiftly as a horse from the Empire which is always good and adds additional mobility to an already mobile unit. If you're not running Black Orcs, giving your boar riders the Banner of Eternal Flame and using them to hunt down regenerating monsters can be a good idea, especially since monsters don't get to stomp them. They will probably have to be a part of a combo charge though in order to pull it off.
Big 'Uns: If you're not running infantry orcs in your army (or fielding Gorbat Ironclaw), then upgrading your unit for the extra WS and S can work. The upgrade is cheaper than it used to be, and gives you two S6, WS4 attacks on the charge alongside the boar's attack, which is quite fearsome. It does increase your chances of taking out monsters such as the Hydra, if the dice are with you, but with the armor save of a Wolf Rider and overall slowness of the Orcs at initiative 2, it just makes the unit too expensive and too fragile for me to feel comfortable with it. With the Big 'Un upgrade for infantry orcs being such an excellent investment, this version for the cavalry orcs just pales in comparison in my opinion.